People tend to divide Robert A. Heinlein's career into three different eras, with the "juveniles," the "slick" science fiction stories, and the bigger, more opnionated novels. But over in Locus Magazine, Gary Westfahl has a theory that's sure to be controversial: Heinlein's career actually divides into a slew of… »11/26/12 4:30pm 11/26/12 4:30pm